Increasingly, product designers with 3D CAD tools are producing curvilinear parts that are very difficult to measure with a single axis device, be it a ruler or a digital calliper gauge.
Coordinate Measuring Machines (CMMs) are a common tool for the metrology of 3D objects. They tend to either use a gantry type mechanism that articulates in a Cartesian fashion about 3 DOF and gathers single point data with the aid of a touch trigger probe, or they use a polar mechanism that articulates like a 6 DOF arm and gathers data from a fixed probe point or laser scanner.
The former Cartesian machines have been refined and value engineered over many years but will always be expensive to build because the component technologies are expensive (sensitive probes, marble beds, air bearings, precise linear encoders, a very stiff frame etc). The polar machines are difficult to engineer accurately because each degree of freedom is attached together in a series chain so that errors accumulate and the total stiffness and accuracy is the sum of all six linkage and encoder inaccuracies. Also radial encoders that maintain micron accuracy at the end of a long lever are very expensive.
The inherent build and accuracy factors result in machines that have an entry level cost of over £10 k, often controlled by complex professional software that not only has a high capital cost but also takes a lot of training to use properly.
The demand for multi axis measurement is expected to grow rapidly, but to date there has not been a tool that is both affordable and easy to use for the small scale or discretionary user. The aim of the present invention is to fill this market niche in that the machine can be built at very low cost, it is robust for use in industrial conditions and new software paradigms make its use fast and uncomplicated.